Hydrocarbon conversion



Jan. 25, 1944. R, B. DAY fr AL 2,339,916

HYDROCARBQN CONVERSION l Filed .my 2e, 1940 Emana/vamp Vil-"OPI Z IN Gffl/VD Enq/MUN@ MBE@ @5 FMP/vaca' 66 FUR/V465 55 Patented Jan. 25, 1944HYDROCARBON CONVERSION Roland B. Day and Elmer R. Kanhofer, Chicago,

Ill., assignors to Universal Oil Products Company, Chicago, Ill., acorporation of Delaware Application July 26, 1940, Serial No. 347,756

2 Claims.

This invention relates to a process for the production of high yields ofhigh octane rating gasoline and more specically to a process involvingboth thermal and catalytic treatments whereby the hydrocarbon oil to beconverted is treated under optimum conditions for conversion to highoctane rating gasoline.

Catalytic cracking as ordinarily conducted does not employ recycling ofinsufdciently converted products to the conversion zone because, as hasbeen found, such insufciently converted hydrocarbons contain a highpercentageof aromatics, cyclo-olens, cyclo-diolens, and diolennhydrocarbon compounds, the tendency of which is to deposit great amountsof carbon or carbonaceous substances upon the catalyst particles, ifrecycled to the catalyst Zone, resulting in a more rapid lowering ofcatalyst activity than is encountered when passing clean unconvertedoils in contact with such catalysts. In order to reduce the formation ofcarbonaceous substances during conversion, resulting in shorterreactivation times and lower peak reactivating temperatures, it is usualto pass the hydrocarbon oil in contact with the catalyst only once andthen thermally crack the insufciently converted oils in a thermalcracking system. In a process employing both thermal and catalyticcracking in the manner above mentioned, the yield and octane of thegasoline product are good but not as good as one might expect from aprocess wherein the catalytic recycle is also catalytically cracked.

In our invention involving both catalytic and thermal treatments Vthetwo steps have been combined in a novel and advantageous manner so thata relatively large proportion of the lnsufliciently convertedhydrocarbons from the catalytic treatment are subjected to thermaltreatment under conditions which favor the removal of the carbon formingconstituents from the insuiciently converted hydrocarbons rather thanthermal cracking to gasoline, although some thermal cracking may occur.By this method compounds undesirable in catalytic cracking, because oftheir tendency to form carbon, such as, for example, diolens, aromatics,cyclo-olens, and cyclodiolens are probably lpolymerized or undergo sometreatment which converts them to higher boiling hydrocarbons which areremoved as residue from the thermal treating system.

In one specific embodiment the invention com prises subjecting arelatively heavy hydrocarbon koil to thermal treatment under viscositybreaking conditions in a heating coil and communicating reactionchambercommingling the conversion products with reaction products formedin the thermal treatment and light and heavy reflux condensates ashereinafter set forth and separating the mixture into non-vaporousliquid residue and vaporous reaction products, recovering the former,fractionating said vaporous reaction products, together with catalyticconversion products formed as hereinafter set forth to separatefractionated vapors boiling substantially in the range of gasoline fromthe higher boiling hydrocarbons, recovering the former, condensing saidhigher boiling hydrocarbons as light and heavy reflux condensates in thefractionating zone, commingling a, portion of said light refluxcondensate vwith a relatively light hydrocarbon oil, heating andvaporizing the mixture and passing the heated vapors in contact with acracking catalyst, fractionating the catalytic conversion products ashereinbefore set forth, subjecting the residual portion of said lightreux condensate to thermal treatment, simultaneously therewithsubjecting said heavy reflux condensate to a separate thermal treatment,commingling the resulting reaction products from the thermal treatmentsof both reflux condensates with the conversion products formed in thethermal treatment of said heavy oil for treatment as hereinbefore setforth.

The primary object of this invention is to provide a combination ofthermal and catalytic cracking wherein provisions are made for handlingheavy distillation residues, such as, for example, topped or reducedcrude oils and at the same time provide for thermally vtreating theinsuiiciently converted hydrocarbons from the catalytic cracking step toelect a removal of undesirable carbon forming constituents contained inthe catalytic conversion products, since these materials if returned tothe catalytic conversion step would result in the formation of largeamounts of carbonaceous substances which deposit upon the catalyticmaterial and lower the activity thereof.

The object of the invention may be accomplished in the following manner.Heavy charging oil comprising, for example, topped or reduced crude oilis subjected to thermal viscosity breaking conditions in a heating coiland communicating reaction chamber. Reaction products formed in thethermal treatment of light and heavy reux condensates in the manner tobe described may be commingled with the reaction products formed in thethermal treatment of the heavy oil before or after introduction of thelatter to the reaction chamber.V The resulting mixture of reactionproducts is supplied to a vaporizing and separating chamber whereinnon-Vaporous liquid residue is separated from the Vaporous reactionproducts and the former recovered. The vaporous reaction products arecommingled with catalytic conversion products formed in a subsequentstep of the process and the mixture fractionated to separate gasolineboiling range hydrocarbons from the heavier hydrocarbons. The heavierhydrocarbons condensed in the fractionating zone are further separatedtherein into light and heavy reux ccndensates. A portion of the lightreflux condensate may be subjected to catalytic treatment above butpreferably is commingled with a light oil chargingstock comprising, forexample, naphtha, kerosene, or gas oil, the mixture heated andvaporized, and the resulting vapors passed in contact with a mass vofcracking catalyst. The catalytic conversion products formed in thistreatment are subjectedto fractionation in the manner previouslydescribed. The heavy reflux condensate is subjected to thermal treatmentin a heating coil and, as above mentioned, may be introduced to thereaction chamber or commingled with the stream of conversion productsleaving the reaction chamber while the residual portion of the lightreflux condensate may be subjected to a separate thermal treatment andthe resulting conversion products commingled with the conversionproducts in Y f the reaction chamber or with those leaving the reactionchamber or, when desired, the residual portion of light refluxcondensate may be commingled with the heavy reflux condensate and thismixture subjected to thermal treatment.

In the preferred embodiment of the invention a relatively larger portionof the insuii'iciently ccnverted hydrocarbons formed in both thecatalytic and thermal treatments is returned to the thermal treatmentascompared to the portion supplied to the catalytic treatment, althoughin some cases substantially equal amounts may be supplied to each step.By selecting conditions in the thermal treatment, which will permitoperating in this manner, theoretically the insuiiciently convertedhydrocarbons make at least one pass through the thermal treating stepbefore being subjected to cracking in the presence of catalyticmaterial. In one or more passes of the insufciently convertedhydrocarbons through the thermal treating step, the undesirable carbonforming constituents which are formed in catalytic cracking are removedand Vrecovered as non-Vaporous liquid residue, whereas if these'materials were returned to catalytic cracking a heavy deposition ofcarbonaceous'substances on the catalytic material would result.

The Vaccompanying diagrammatic drawing illustrates in conventional side`elevation one specific form of the apparatus which may be employed toaccomplish the objects of the invention.

Referring to the drawing, heavy charging oil comprising, for example, atopped or reduced crude oil, is introduced through line I containingvalve 2 to pump 3 which discharges through line It containing Valve 5into heating coil 6. The oil in passing through heating coil 6 is raisedto a viscosity breaking temperature ranging, for example, from 800 to1000 F., or thereabouts, by means of heat supplied fromfurnace 1,preferably while maintaining the oil under a superatmospheric pressureranging, for example, from `.100 to 600 pounds or ymore per squareinch.v The heated Yreaction products leaving heating coil 6 arel'directed through -1ine'8 containing valve f9 CFI into reaction chamberI Il. In the case here illustrated, other reaction products formed inthe manner to be described may be supplied to reaction chamber I andcommingled therein with the reaction products introduced as abovementioned wherein substantial further conversion results. Reactionchamber I8, in the case here illustrated, is preferably operated at asuperatmospheric pressure of approximately the same order or slightlyless than that employed in the heating coils from which the reactionproducts are derived and is preferably insulated to reduce radiationlosses therefrom, although no insulation appears in the drawing.

Reaction products leaving chamber I B are directed through line IIcontaining valve I2 and, when desired, may be commingled with reactionproducts formed in the manner to be described, which are not introducedto chamber I0, and the resulting mixture thereafter introduced tovaporizing and separating chamber I3. Chamber I3, in the case hereillustrated, is preferably operated at a substantially reduced pressurerelative to that employed in chamber I0, being of the order of to 200pounds or more per square inch. Va-

- porous and liquid reaction products are substantially separated inchamber I3 and the latter substantially further vaporized to form anonvaporous liquid residue which is removed therefrom by way of line I4containing valve I5, and recovered as a product of the process orsubjected to any desired further treatment.

Vaporous reaction products leaving chamber I3, including vapors evolvedtherein, are directed through line IS containing valve I'I, commingledwith'catalytic conversion products formed in the manner to be described,and the mixture introduced tov fractionator I8. Fractionator I8,together with the condensing and collecting equipment in communicationtherewith, may be operated at a ,pressure of substantially the sameorder as that employed in chamber I3, but in case lower pressures areemployed in the catalytic conversion zone fractionator I8 may beoperated Aat a pressure comparable therewith. Vaporous reaction productsand catalytic conversion products are fractionated in fractionator I8 toseparate fractionated vapors boiling substantially in the range ofgasoline from the higher boiling insuiciently converted hydrocarbons.

Fractionated vapors separated in fractionator I8 are-conducted throughline I9 containing valve `2li to cooling and condensation in condenser2l. The distillate, together with undissolved and uncondensed gases incondenser 2|, is directed through line 22 containing valve 23 intoreceiver 24 whereinvthe distillate and gases are collected andseparated. Undissolved and uncondensed gases collected and separated inreceiver 24 are removed therefrom by way of line 25 containing valve 25,.recovered as a yproduct of the process or subjectedV to any desiredfurther treatment. A portion'of the distillate collected andseparated inreceiver 24 is returned to .the upper portion of fractionator I8 by wellknown means, not shown, to serve as a refluxingv and coolingmedium andthe residual portion thereof is removed from receiver 24 by'way of line2I containing valve y23, recovered as a 'product of the process -orsubjected to any desired further treatment.

The heavy insufficiently converted hydrocarbons separated inAfractionator I8 are condensed therein'into light and heavy reiiuxcondensates, the-lighter reflux condensate preferably comprisinghydrocarbons boiling, below 600 F. while the heavy reux condensateincludes those. hydrocarbons boiling above 600 F. Light reiiuxcondensate separated in fractionator I8 is directed through line 29containing valve 30 to pump 3|. Pump 3l discharges through line 32 andall of the light reflux condensate may be directed through valve 33 intoline 31 and thereafter subjected to catalytic cracking in the manner tobe described. Preferably, however, only a portion of the light refluxcondensate in line 32 is directed through valve 33 to catalytic crackingwhile the residual portion thereof is subjected to thermal treatment inthe manner to be described. The light reiiux condensate supplied to line31 by Way of line 32 may be introducedto heating coil 39 alone, however,in some cases, it may be commingled with a relatively light hydrocarbonoil, such as, for example, gas oil, naphtha, r kerosene introduced froman exterior source by way of line 34, valve 35, pump 36, line 31, andvalve 38 and the mixture supplied to heating coil 39. When desired,steam and/or light gaseous products, the latter comprising either thoseformed in the process or light gases introduced from an exterior source,are commingled with the hydrocarbon oil in line 31 to aid insubstantially completely vaporizing said hydrocarbon oil and also as ameans for reducing the total pressure on said oil. Heating coil 39receives heat from furnace 40 whereby the oil introduced thereto issubstantially completely vaporized and heated to a temperature ranging,for example, from 800 to 1200 F. preferably while maintaining said oilat a pressure ranging, for example, from substantially atmospheric to200 pounds or more per square inch.

The heated reactants leaving coil 39 are directed through line 4Icontaining valve 42 into reactor 43 which contains catalytic materialcapable of eiecting the desired conversion reaction. In the case hereillustrated, reactor 43 may comprise, for example, a zone of the heatexchanger type wherein the catalyst is contained in a plurality ofelongated tubular elements of relatively small diameter and whereinprovisions are made for passing some suitable heat convective mediumsuch as combustion gases in contact with the exterior of said elongatedtubular elements Whereby to supply heat to the reactants duringconversion and to effect cooling during reactivation of the mass ofcatalytic material. Reactor 33, on the other hand, may comprise acylindrical vessel which is well insulated to reduce radiation lossesand which contains one or a plurality of beds of catalytic materialwherein the reaction may be accomplished substantially adiabatically.

In the catalytic cracking of hydrocarbons relatively large amounts ofcarbonaceous substances are formed which deposit upon the catalyticmaterial thereby reducing its active surface and necessitatingreactivation at periodic frequent intervals. T'he invention contemplatesreactivating the used catalytic material in the usual manner, such as,for example, by passing oxygen-containing reactivating gases in contactwith the used catalytic material and removing carbonaceous substances ascombustion gasesv along with the spent reactivating gases. It isdesirable therefore, in order that the operation may be carried out as acontinuous process to employ at least two reactors, and in someinstances more than two reactors, so that while the catalytic materialin one reactor is being used for effecting conversion of the hydrocarbonreactants the catalytic material in the other or others may beundergoing reactivation.

Catalysts which have been found to be effective in the catalyticcracking of hydrocarbon vapors may comprise pellets or granules ofsilica or other siliceous and refractory materials composited withcompounds selected from the group consisting of alumina, zirconia, andthoria. In addition, the hydrosilicates of alumina, acid treated clays,or the like, have also been found to be effective in the crackingtreatment of hydrocarbon vapors. Although the catalysts above recitedare generally considered to be the preferred catalysts their use is notto be construed as a limiting feature, for various other catalysts wellknown to those in the art may be employed within the broad scope of theinvention.

Conversion products leaving reactor i3 are directed through line 44containing valve 45 into line IS, commingling therein with the vaporousreaction products formed in the manner previously described, and themixture supplied to fractionator I8 in the manner previously described.

The residual portion of the light reux condensate in line 32 may bedirected through line 46 containing valve 41 into line 59 where itcommingles with the heavy reiiux condensate for treatment in the mannerto be described. Preferably, however, the remaining light reiiuxcondensate in line 32 issubjected to a separate thermal treatment whichis accomplished by directing the same through line t3 containing valve59 to pump 50. Pump 50 discharges through line 5I containing valve 52into heating coil 53 which receives heat from furnace 5E. Preferablyalso, in order that substantially all of the insufficiently convertedhydrocarbons formed in both the thermal and catalytic treatments may besubjected to some thermal treatment, the quantity of insuicientlyconverted hydrocarbons including both light and heavy reflux condensatesreturned to the thermal treatment should be equal to, if not greaterthan, the amount of light reflux condensate directed through valve 33 inline 32 for catalytic cracking in the manner previously described.

Light reflux condensate passing through coil 53 is subjected toconditions of temperature and pressure favorable to the conversion ofthe undesirable compounds present therein which are bad carbon iormerswhen brought in contact with the catalytic materials whereby thesematerials are converted into heavier hydrocarbons and subsequentlyremoved as liquid residue in vaporizing and separating chamber I3.Temperatures to which the light reilux condensate may be heat ed in coil4I may range from 800 to 1000" F., or thereabouts, while employing asuperatmospheric pressure ranging, for example, from to 1000 pounds ormore per square inch. The heated products leaving coil 53 by way of line55 may be directed through valve 56 into line 53 wherein they maycommingle with the reaction products from the thermal cracking of theheavy reflux condensate formed in the manner to be described and themixture introduced to chamber IU. In another manner of operation thereaction products leaving coil 53 by way of line 55 may be directedthrough line 51 containing valve 58 into line 68 by means of which theyare supplied to line II, commingling therein with the reaction productsleaving chamber I0 for treatment in the manner previously described.

Heavy reflux condensate leaving fractionator I8 is directed through line59 containing valve 60 to pump 6I or when desired, the heavy refluxcondensate in line 59 Amay be commingled with the light refluxcondensate supplied thereto by Way of line 45 in the manner previouslydescribed and the mixture supplied to pump 6|. Pump 6l dischargesthrough line 62 containing valve 63 into heating coil 04 Which receivesheat from furnace 65. The oil in passing through coil 65 is raised to athermal cracking temperature ranging, for example, from 800 to 1050 F.,or thereabouts, While being maintained at a superatmospheric pressureranging from 100 to 600 pounds or more per square inch. The reactionproducts leaving coil 64 by Way of line 66 may be directed through valveSi into reaction chamber l for treatment in the manner previouslydescribed or they may be directed through line 68 containing valve 69into line Il Where they commingle with the reaction products leavingchamber l0.

An example of one specic operation of the process as it may beaccomplished in an apparatus such as illustrated and above described isapproximately as follows: Heavy charging oil comprising a 25 A. P. I.gravity Mid-Continent reduced crude oil is heated to a temperature of890 F. While employing a pressure of 200 pounds per square inch on theoutlet of the heating coil. The reaction products formed in the heatingcoil are commingled with other reaction products formed by the thermaltreatment of light and heavy reflux condensates in the manner to bedescribed and the mixture introduced to a reaction chamber operated at asuperatmospheric pressure of 200 pounds per square inch.

The reaction products leaving the reaction chamber are supplied to avaporizing and separating chamber operated at a superatmosphericpressure of 40 pounds per square inch wherein vaporous reaction productsare separated from the non-vaporous liquid residue formed in theoperation and the latter recovered as a product of the process. Vaporousreactie-n products separated as above mentioned are commingled withcatalytic conversion products formed in the manner to be described andthe mixture fractionated at a superatmospheric pressure of approximately40 pounds per square inch to separate vapors of approximately 400 endpoint from the higher boiling insuflciently converted hydrocarbons. Thevapors separated as above mentioned are subjected to cooling andcondensation and the resulting distillate and gas collected andseparated.

The higher boiling insuilciently converted hydrocarbons are condensed asreflux condensate in the fractionator and the total reflux condensatesubstantially further separated into light reflux condensate ofapproximately 550 F. end point and heavy reux condensate which includesall of the hydrocarbons boiling above 550 F. Approximately one-half ofthe light reflux condensate separated as above mentioned is commingledwith an equal volume of 33 A. P. I. gravity Mid-Continent gas oil andthe mixture heated and vaporized at a temperature of 980 F. and at apressure of 45 pounds per square inch. The heated vapors are passed incontact with a mass of synthetically prepared silica-alumina catalyst ata liquid hourly space velocity of approximately L2 and the catalyticconversion products formed are fractionated in the manner previouslydescribed.

The residual portion lof the light reux condensate Anot subjected tocatalytic cracking is treated thermally at a temperature of approxi-.mately 850 F. and under a superatinospheric pressure of approximately300 pounds per square inch. The reaction products formed by this thermaltreatment vare commingled with other .reaction products in the reactionchamber as above mentioned.

Heavy reflux condensate separated as above mentioned is subjected rtotherma1 treatment in a heating coil at a temperature of 920 F. whilemaintaining the oil under a superatmospheric pressure of 400 pounds per.square inch. The reaction products leaving the heating coil arecommingled with the reaction products formed in the kthermal treatmentsof the charging stock and the light reflux condensate and the .mixturesubjected to prolonged treatment in the reaction chamber as abovementioned.

From an operation vemploying conditions as above described one mayobtain approximately 64.0% of 400 F. end point gasoline of approximately'75.5 octane number, 23.0% of nonvaporous liquid residue atapproximately 10 F. A. P. I. gravity, the balance being principallycarbon, gas, and loss.

We claim as our invention:

1. A process for the conversion of hydrocarbon oil, which comprisesthermally cracking a relatively heavy oil, catalytically cracking arelatively light oil, combining cracked vapors from both cracking stepsand fractionating the same to form light and heavy reux condensate,recovering the fractionated vapors, supplying a regulated quantity ofsaid light reflux condensate to the catalytic cracking step, subjectinganother quantity of said light reiiux condensate and said heavy refluxcondensate to thermal cracking independently of said relatively heavyoil and independently of each other to form cracked vapors and toconvert undesirable carbon forming constituents into liquid residue,separating liquid residue from the cracked vapors, and supplying thelast mentioned cracked vapors to the fractionating step.

2. A process for the conversion of hydrocarbon oil which comprisesthermally cracking a relatively heavy hydrocarbon oil to form crackedvapors having a lower-average boiling point than said oil, separatingliquid residue from said cracked vapors, fractionating the latter toform light and heavy reflux condensates, recovering the fractionatedvapors, dividing the light reflux condensate into at least threeportions of like composition, subjecting one of said portions tocatalytic cracking, supplying resulting conversion products to thefractionating step, combining another of said portions With said heavyreflux condensate and subjecting the mixture to thermal cracking,independently of said heavy oil and subjecting still another of saidportions to thermal cracking independently of said heavy oil and of saidmixture, to form cracked vapors and to convert undesirable carbonforming materials into liquid residue, separating the last named liquidresidue from the last mentioned cracked vapors, and supplying the latterto the iractionating step.

ROLAND B. DAY. ELMER R. KANHOFER.

CERTIFICATE OF CORRECTION. Patent No. 2,559,915. January 25, 19ML.ROLAND B. DAY, ET AL.

It 1s hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line 1b., for "above" read -alone; and that thesaidLetters Patent should 'be read with this correction therein that thesame may conforml to the record of` the case in the Patent Office.

signed and sealed this 25rd day of may, A. D. 191m.

Leslie Frazer (Seal) Acting Commissioner of Patents.

